Turkey on Sunday eased a curfew in part of Diyarbakir, the main city in the country’s Kurdish-dominated southeast, but imposed it in two others as a prelude to fresh army operations against rebels.

Turkish armed forces have been waging a major — and controversial — offensive against the outlawed Kurdistan Workers’ Party (PKK) since December, imposing strict 24-hour curfews in a number of towns and cities in the southeast.

From 8:00 am (0600 GMT) on Sunday residents of part of Diyarbakir’s historic Sur district were allowed back onto the streets, where buildings have been badly damaged in the operation, an AFP journalist in the city said.

Other areas of Sur, a UNESCO world heritage site, remain under curfew to allow the authorities to “capture terrorists” and “clear explosives and booby-traps”, according to the local governor.

But as restrictions were eased in Diyarbakir, the authorities announced the cities of Yuksekova, near the Iranian border, and Nusaybin, on the frontier with Syria, would be under curfew from Sunday evening to “restore order and security” after “a rise in terrorist activity”.

Ankara has vowed to wipe out the PKK, classed as a terrorist organisation by Turkey and its Western allies, and said “clean-up” operations in Yuksekova, Nusaybin and Sirnak, a third Kurdish city, are imminent.

The police and army launched an operation in the narrow streets of Sur in early December aimed at retaking control of areas seized by armed PKK activists, who dug trenches and put up barricades.

Critics say the clashes have caused major damage and forced nearly 50,000 people in Sur from their homes since the start of December. Up to 70,000 people were living in the area before the violence erupted.

Army high command said this week its operation in Sur had killed 279 members of “the separatist terrorist organisation”, the PKK, but gave no toll for security forces. Local media have put the figure in the dozens.

The pro-Kurdish Peoples’ Democratic Party (HDP) says dozens of civilians have also been killed.

Violence flared last summer between Kurdish rebels and government forces after a deadly bombing in a Kurdish majority town, shattering a 2013 ceasefire reached after secret talks between PKK leader Abdullah Ocalan and Ankara.

Over 40,000 people have been killed since the PKK took up arms in 1984 demanding an independent state for Kurds. Since then the group has narrowed its demands to greater autonomy and cultural rights.